21521163 has 4 divisors (see below), whose sum is σ = 28694888. Its totient is φ = 14347440.

The previous prime is 21521141. The next prime is 21521183. The reversal of 21521163 is 36112512.

It is a semiprime because it is the product of two primes.

It is not a de Polignac number, because 21521163 - 2⁸ = 21520907 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21521183) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3586858 + ... + 3586863.

It is an arithmetic number, because the mean of its divisors is an integer number (7173722).

Almost surely, 2^21521163 is an apocalyptic number.

21521163 is a deficient number, since it is larger than the sum of its proper divisors (7173725).

21521163 is an equidigital number, since it uses as much as digits as its factorization.

21521163 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7173724.

The product of its digits is 360, while the sum is 21.

The square root of 21521163 is about 4639.0907514296. The cubic root of 21521163 is about 278.1560938682.

Adding to 21521163 its reverse (36112512), we get a palindrome (57633675).

The spelling of 21521163 in words is "twenty-one million, five hundred twenty-one thousand, one hundred sixty-three".